#define _CRT_SECURE_NO_WARNINGS 1
#include <iostream>
using namespace std;
const int N = 1010;
int n, m;
char s1[N];
char s2[N];
int dp[N][N];
int main()
{
	cin >> n >> m;
	for (int i = 1; i <= n; i++) cin >> s1[i];
	for (int i = 1; i <= m; i++) cin >> s2[i];
	for (int i = 1; i <= n; i++)
	{
		for (int j = 1; j <= m; j++)
		{
			if (s1[i] == s2[j]) dp[i][j] = dp[i - 1][j - 1] + 1;
			else dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);
		}
	}
	cout << dp[n][m] << endl;
	return 0;
}